/*
 * Copyright 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.compose.runtime

import kotlin.test.Test
import kotlin.test.assertTrue
import kotlinx.coroutines.CoroutineStart
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.launch
import kotlinx.coroutines.test.UnconfinedTestDispatcher
import kotlinx.coroutines.test.runTest
import kotlinx.coroutines.withTimeout

@ExperimentalCoroutinesApi
class LatchTest {
    @Test
    fun openDoesntSuspend() =
        runTest(UnconfinedTestDispatcher()) {
            val latch = Latch()
            assertTrue(latch.isOpen, "latch open after construction")

            val awaiter = launch(start = CoroutineStart.UNDISPATCHED) { latch.await() }
            assertTrue(awaiter.isCompleted, "await did not suspend")
        }

    @Test
    fun closedSuspendsReleasesAll() =
        runTest(UnconfinedTestDispatcher()) {
            val latch = Latch()
            latch.closeLatch()
            assertTrue(!latch.isOpen, "latch.isOpen after close")

            val awaiters =
                (1..5).map { launch(start = CoroutineStart.UNDISPATCHED) { latch.await() } }
            assertTrue("all awaiters still active") { awaiters.all { it.isActive } }

            latch.openLatch()
            withTimeout(500) { awaiters.map { it.join() } }
        }
}
